title: A novel bacterial enzyme with D-glucuronyl C5-epimerase activity.
abstract: Glycosaminoglycans are biologically active polysaccharides that are found ubiquitously in the animal kingdom. The biosynthesis of these complex polysaccharides involves complicated reactions that turn the simple glycosaminoglycan backbone into highly heterogeneous structures. One of the modification reactions is the epimerization of D-glucuronic acid to its C5-epimer L-iduronic acid, which is essential for the function of heparan sulfate. Although L-iduronic acid residues have been shown to exist in polysaccharides of some prokaryotes, there has been no experimental evidence for the existence of a prokaryotic D-glucuronyl C5-epimerase. This work for the first time reports on the identification of a bacterial enzyme with D-glucuronyl C5-epimerase activity. A gene of the marine bacterium Bermanella marisrubri sp. RED65 encodes a protein (RED65_08024) of 448 amino acids that has an overall 37% homology to the human D-glucuronic acid C5-epimerase. Alignment of this peptide with the human and mouse sequences revealed a 60% similarity at the carboxyl terminus. The recombinant protein expressed in Escherichia coli showed epimerization activity toward substrates generated from heparin and the E. coli K5 capsular polysaccharide, thereby providing the first evidence for bacterial D-glucuronyl C5-epimerase activity. These findings may eventually be used for modification of mammalian glycosaminoglycans.
authors.affiliation: Laboratory of Microbiology, Wageningen University, 6703 HB Wageningen, The Netherlands.
authors.forename: John
authors.initials: J
authors.lastname: Raedts
authors.forename: Magnus
authors.initials: M
authors.lastname: Lundgren
authors.forename: Servé W M
authors.initials: SW
authors.lastname: Kengen
authors.forename: Jin-Ping
authors.initials: JP
authors.lastname: Li
authors.forename: John
authors.initials: J
authors.lastname: van der Oost
mesh_terms: D000818:Animals; D059001:Aquatic Organisms / Q000201:enzymology / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics*; D002238:Carbohydrate Epimerases / Q000737:chemistry* / Q000235:genetics*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D020563:Gammaproteobacteria / Q000201:enzymology* / Q000235:genetics*; D006025:Glycosaminoglycans / Q000737:chemistry / Q000235:genetics; D006801:Humans; D051379:Mice; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D006025:Glycosaminoglycans; D011994:Recombinant Proteins; C020341:glucosaminoglycans; D002238:Carbohydrate Epimerases
keywords: Bermanella marisrubri; Capsular Polysaccharide; Carbohydrate Biosynthesis; Glycosaminoglycan; Heparan sulfate; Heparin; Microbiology; d-Glucuronyl C5-epimerase; l-Iduronic acid